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 mikahs June 10, 2011 09:00

Vortex Street with pisoFoam

Hello people...

I am fairly new to CFD and OpenFOAM, so I am not very sure about some results I am getting while simulating a vortex street with a flow around a cylinder.

I was asked to use pisoFoam with laminar flow, and simulate a given mesh (with the cylinder) at Re=20, Re=200 (the vortex street should appear here) and Re=2000.

At Re=20, I had no problems with convergence, with 8000 Iterations my residuals were below 10E-5.

However at Re=200 and at Re=2000 the residuals oscillate asymptotically.

Example: Re=200

http://img707.imageshack.us/img707/7...erre200.th.jpg

I would like to know whether this behaviour in my residuals is normal for vortex street calculations, or if I am really having some problems of some other kind.

Ah, and I forgot to say... Courant-Nr<1 ... :/

Code:

```ddtSchemes {     default        Euler; } gradSchemes {     default        Gauss linear;     grad(p)        Gauss linear;     grad(U)        Gauss linear; } divSchemes {     default        none;     div(phi,U)      Gauss limitedLinearV 1;     div(phi,k)      Gauss limitedLinear 1;     div(phi,epsilon) Gauss limitedLinear 1;     div(phi,R)      Gauss limitedLinear 1;     div(R)          Gauss linear;     div(phi,nuTilda) Gauss limitedLinear 1;     div((nuEff*dev(grad(U).T()))) Gauss linear; } laplacianSchemes {     default        none;     laplacian(nuEff,U) Gauss linear corrected;     laplacian((1|A(U)),p) Gauss linear corrected;     laplacian(DkEff,k) Gauss linear corrected;     laplacian(DepsilonEff,epsilon) Gauss linear corrected;     laplacian(DREff,R) Gauss linear corrected;     laplacian(DnuTildaEff,nuTilda) Gauss linear corrected; } interpolationSchemes {     default        linear;     interpolate(U)  linear; } snGradSchemes {     default        corrected; } fluxRequired {     default        no;     p              ; }```
Code:

```solvers {     p     {         solver          PCG;         preconditioner  DIC;         tolerance      1e-06;         relTol          0.1;     }     pFinal     {         solver          PCG;         preconditioner  DIC;         tolerance      1e-06;         relTol          1e-4;     }     U     {         solver          PBiCG;         preconditioner  DILU;         tolerance      1e-05;         relTol          0;     } } PISO {     nCorrectors    3;     nNonOrthogonalCorrectors 0;     pRefCell        0;     pRefValue      0; }```

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